Physicochemical Properties of Deuterated Compounds. 8th Communication. The kinetic isotope effect for the reaction of hydrogen atoms with methylcyclohexane and perdeuteromethylcyclohexane in the gas phase
✍ Scribed by Noboru Fujisaki; Amanz Ruf; Tino Gäumann
- Publisher
- John Wiley and Sons
- Year
- 1985
- Tongue
- German
- Weight
- 558 KB
- Volume
- 68
- Category
- Article
- ISSN
- 0018-019X
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
Using H‐atoms produced in the radiolysis of water vapour, we determined the kinetic isotope effect for the reaction
where RH and R′D are methylcyclohexane and perdeuterated methylcyclohexane, respectively. The result obtained from the isotope competitive method can be expressed with the Arrhenius‐type equation k~H~/k~D~ = (0.51 ± 0.04) exp[(8.58 ± 0.25) kJ mol^−1^/RT] over the temperature range from 363 to 483 K. The occurrence of H abstraction from primary, secondary, and tertiary CH bonds in methylcyclohexane is taken into consideration in the interpretation of the Arrhenius‐type expression obtained. Theoretical interpretation of the kinetic isotope effect has been achieved on the basis of the transition‐state theory and a semiempirical London‐Eyring‐Polanyi‐Sato potential‐energy surface. The tunnel effect is found to play a role in the H‐abstraction. Several methods for estimating the tunnel correction factors have been discussed.